Gray water reuse studied in Cal. homes

September 1996

U.S. Water News Online

SACRAMENTO, Calif. -- The California Department of Water Resources (DWR) has begun a two-year study to document the effects of using gray water for home landscaping systems here.

The department is working with several local water districts to install gray water systems at single-family homes -- 10 have been selected across a range of modest to affluent neighborhoods in the district -- to document water savings, analyze customer satisfaction, and determine the effects of gray water on the landscape.

According to Marcia Prillwitz, Landscape Program Manager at DWR who is in charge of the Gray Water Program, the use of gray water for landscape irrigation purposes has been legal in California since 1994, but so far its use has been limited to single-family dwellings. DWR, she says, is planning to expand their current Gray Water Guide -- a practical manual on how to set up such a system -- for multi-family, commercial, and industrial users.

"We are currently revising the regulations for this purpose," said Prillwitz. "We expect the new regulations and guide book to be available by January of 1997."

Under the program, a family or housing unit uses its own wastewater -- excluding sewage -- to irrigate its own landscape, thus reducing water consumption and saving considerably on water bills.

The two-year study, which began this July, should for the first time give DWR statistics on gray water use -- its benefits, cost, and effect on soils and plants. It will help answer such questions as, how much gray water is generated by a family, and therefore how efficient and effective the entire system is.

Prillwitz says that investment in a gray water system for residential use can cost anywhere from $500 to $5000, depending on the sophistication of the system installed. The participants in this study are getting some financial assistance from DWR, as well as their local water district, to install the system.

Since participants range from owners of modest to more affluent dwellings, she said, the range of systems should be great enough to get an accurate sampling of system types and document the comparative results.

"We hope this will give us a better idea of the benefits different systems can offer," she said, "as well as the benefit -- and cost -- of the gray water system itself."

Prillwitz says other states, including Texas, Arizona, New Mexico, Oregon, Washington, and Florida are currently looking at such gray water programs, but they have yet to legalize its use.

In California, she said, there are already a couple of companies specializing in gray water technology, but, she added, "we wish there were more." As the practice becomes more common, she said, the manufacturing base will no doubt grow.

For a copy of DWR's Gray Water Guide write to:

Marcia Prillwitz, Landscape Program Manager Calif. Department of Water Resources Central Records 1416 9th St. Sacramento, CA 95814
e-mail address: MarciaP@water.CA.gov



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